Electric furnace



2 SHEETS-SHEET I- ATTORNEY Feb. 13, 1923.

T. A. REID.

ELECTRIC FURNACE FILED APH. 25, 1921.

WITNESSES: #62M Feb; 13, 1923. 1,444,939, T. A. REID.

ELECTRIC FUR'NACE.

FILED APR. 25| 1921- 2 SHEET$-SHEET 2* 30 26 2Q 3o 29L Hg v Hg 7 WITNESSES: INVENTOR ATTORNEY Patented Feb. 13, 1923.

UNITED STATES PATENT OFFICE.

THOMAS A. REID, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMIIPANY, A CORPORATION 0F PENNSYLVANIA.

ELEc'rarc FURNACE.

Application led April 25, 1921. Serial No. 464,308.

To all whom it may concewt Be it known that I, THOMAS A. REID, a citizen of thel United States, and` a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a newl and useful Improvement in Electric Furnaces, of which the following is a speciication.

My invention relates to electric furnaces and particularly to electric-resistance furnaces, and it has for its object to provide an electric-resistance furnace embodying a relatively simple supporting means for a metallic resistor.

In practicing my invention, I provide a refractory member with a plurality of slots of substantially L-shape in which a metallic resistor member may be inserted.

In one form of my invention, the refractory'members are of such shape and are so located in the walls of the furnace chamber that they cannot be quickly removed therefrom, while, in a modified form, they are of such shape and are s o located as to be easily and quickly removed. In either form, the metallic resistor member may be easily and quickly removed and yreplaced without disturbing the resistor-supporting member itself. l

In the drawings,

Figure 1 is a view, in vertical'section, of a horizontal electric furnace comprising the device embodying my invention;

Fig. 2 is a view, in vertical section on the vline II-II of Fig. 1, of a portion -of the furnace; i

Fig. 3 is a view, in horizontal section on the line III-III of ig. 4, of a verticalchamber furnace comprisingthe device e'mbodying my invention; 4

F ig. 4 is a vieW,-in vertical section, of a furnace comprising the device embod 'ng mv invention taken on the line IV--I of Fig. 3; l

Fig. 5 is a view, in vertical section of a horizontalchamber electric furnace comprising a modified form of the device embodying my invention; v

Fig.'6 is a view, in vertical section, of a portion of the furnace illustrated in Fig. 5, taken on the line VI-VI thereof;

Fig. 7 is a view substantially similar to F ig. 6 and illustrating a different method of supporting the metallic resistor;

Fig. 8 is a view,.in end elevation, of the portion of a furnace illustrated in Fig. 7, and

Fig. 9 is an enlarged view, in side elevation, of a portion of a resistor-supporting member embodying my invention.

Referring more particularly to Fig. 1, an electric furnace 10 comprises an outer metallic framework 11 which is provided with suitable supporting members 12. A lining of .suitable heat-insulating material is located within the framework 11 and comprises side walls 13, a bottom wall 14 and a roof 15 suitably `spaced apart to form a furnace chamber 16. The cover member 15 is preferably made in the form of an arch, and suitable cooperating refractory mem* bers 17 and 18 are provided to permit of combining the roof 15 with the side walls 13 to form the chamber 16.

If it is desired to provide resistors at the bottom of the furnace, I may use the type of heating element disclosed in a copending application, Serial No. 449,685, iiled by O. A. Colby and myself, on March 5, 1921, and assigned to 'the Westinghouse Electric & Manufacturing Co., (Case 8720). The heat-v ing elements comprise fiat refractory plates 19 which kare provided, on one surface there of, with a plurality of integral alined projections between which may be located the preformed metallic resistor member 20.

The furnace chamber 16 is provided with a high-heatiesisting lining 22 of any suitable or desired form, and a plurality of relatively narrow elongated refractory resistorsupportin-g members 21 located at spaced'intervals in the lining 22. Each of the members 21 is provided with a plurality of spaced Yslots 23, of substantially L-shape, in one surface thereof, the inner end of the slot being slightly enlarged as may best'be seen by refxerence to Fig. 9, for a purpose to be hereinafter set forth. A

A*It may be noted that the member 21, with its lurality of slots 23, may be said to have a p urality of symmetrical inte al projections in one surface, each of wgir tions has a single overhanging flange.k

ch projec- Y In the roof of the furnace, the shape of The resistance member 24. comprises a rod or bar of any suitable resistance material, such as nichrome, and is bent to suitable shape and dimensions before being placed in the slots 23. As may best be noted by reference to Fig. 2, the resistor member 24 comprises a number of spaced and substantially parallel extending convolutions with integral end connections.

The members 21, located at the sides and in the roof of the furnace, are spaced apart a suitable distance 'which is determined with reference to themetallic resistor member 24 located in the slots 23. It is, of course, ap-V parent that the distance between the successive members 21 may vary in accordance with the thickness of the, resistance member itself but it is desirable thatthe distance between successive members shall be such as to preclude the deformation of the convolutions of the resistor member when the same is heated by an electric current.

If the height of the furnace chamber' is slightly greater than the height of the member 21, a suitable refractory brick or block 25 may be provided at each side, as indicated in Fig. 1.

Figs. 3 and 4 illustrate the use of the device embodying my invention in a verticalchambcr electric furnace. A suitable metallic frame 11, and an outer layer 13 of heatinsulating bricks may be provided subst-antially the same as in the case of the furnace illustrated in Figs. 1 and 2. Spaced apart at Isuitable intervals inside of the lining 13, are complete circles formed 0f a plurality of suitably shaped resistor-supporting members 21 each of which is provided with a plurality of slots 23 of substantially L-shape. A lining 22 is located inside of the lining 13 and comprises suitable high-temperature-resisting refractory bricks or blocks. Located in the slots 23 is a suitable resistor member 24 which is formed in substantially the same shape and manner as hereinbefore described in connection with the furnace illustrated in Fig. 1. It is, of course, apparent that the weight of the resistor member 24 is carried. by the upper of the two cooperating rings of members 21 which are associated wlth any one vof the resistor members 24.' It is, of course, also apparent that the furnace illustrated in Figs. 3 and 4 may be made of any suitable or desired height. I

Referring more articularly to themodifications illustrate in Figs. 5 and 6, the furnace comprises an outer metallic frame-v work or casing 11 having suitable supports 12. A. lining of heat-insulating material iuside of the casing 11 comprises side Walls 13, a bottom wall 14 and an arched roof 15', each of which may be formed of suitably shaped and dimensioned bricks or' slabs. The side walls, bottom and roof enclose a furnace chamber 16 on the bottom of which may be located a heat-ing element comprising Hat refractory resistor-supporting members 19, hereinbefore described, and a suitable metallic resistor 20. A plurality of spaced resistor members 26 are located inside of'the Walls 13, the members 26 being substantially of T-shape in lateral cross section and provided, at their inner surface, With a plurality of spaced slots 23 of substantially L-shape, as hereinbefore described in connection with the members illustrated in Fig.

A lining 27 is provided inside of the side walls 13 and comprises a plurality of suitably shaped bricks or blocks of a refractory higli-temperature-resisting material, built up in spaced-apartk sections, as indicated in Fig. 6. The end bricks of each section are provided with a shoulder portion to cooperate with the over-hanging portions of the members 26 to hold them in their operative position. Sufficient clearance may be provided between linings 13. and 27 and,between the success-ive sections of the inner lining and the members 26 to permit of removing them by sliding them vertically upwardly; it being assumed, of course, that the roof member or, at least, a portion thereof, has

been removed to permit of thus moving the members 26. Those portions of the Outer side Walls adjacent the members 26 may be built as separate andl easily removable sections. In case it becomes necessary to remhve one of the 'members 2,6, a part or all of a corresponding removable Wall section may be taken out and the member 26`may then be moved horizontally outward.

This construction is also applied to the resistor-supportin members 26 mounted in the roof by buil ingthe roof or cover in sections and by providing removable nembers 28 that are located immediatelyabove the removable members 26. In case it becomes necessary to replace one of the members 26 that are located in the covervmember or roof cf the furnace', it is only nec essary to remove a sufficient number of the y I blocks 28, after which the. damaged mem-v 4ber 26 may be moved outwardly through It may be noted that the method of mounting the preformed resistor member 24 in the cooperating members 21 and 26 is by first inserting the convolutions in thoseV parts of "the slots 23 which extend to4 the outer surface of" the members, then mov- V ing the convolutions 'away from ,the sur-l face and-then substantiall downwardly in the casey of the horizonta chamber of the furnace, or to either the right or to the left j of the vertical center line of the chamber of the furnace.

l The convolutions of the resistonmember 24 are located in -the enlarged inner end portion of the slot 23 and it may be noted that the inner portion of the slots 23 are so located that the resistor member 24 is precluded from accidentally being dislodged from the slots as the weight of the resistor tends to maintain it in the enlarged end portion of the Slot 23.

In the modifications illustra-ted in Figs. 7 and 8, an insulated auxiliary metal rod 29 is located in the slots 23 in the members 26 and a metallic resistor member 30 of ribbon shape is supported by the insulated rods 29.

If desired', the resistor member 30 may be bent in sinuous form, as illustrated in Fig. 7, in order to permit of mounting a greater` length of resistor member in a given space. This permits of using av resistor member of greater cross section without decreasing the resistance of the complete heating element below a predetermined value, as mayl be necessary in connection with an electric supply circuit of a given voltage. The mounting of the resistor members 26 and of the members 28l is substantially the same as hereinbefore described in connection with Figs. 5 and 6. It may be noted that the slot 23 in the member 26 is in a different plane from that illustrated in Fig. 6 and that the member 26 may be made relatively narrow, but these are details of construction that in no wise affect the inventive idea.

The device embodying my invention thus provides a relatively simple refractory resistor-supporting member which may be combined in any suitable or desired locations in the furnace chamber to form a set of cooperating metallic-resistor-supporting means. It ma be notedn also that, in the modification il ustrated, I have provided a quickly removable resistor-supporting means which may be adapted to any size or vshape of electric furnace. Further, the device embodying my invention provides a resistorsupporting means which permits the quick insertion and removal of a preformed metallic resistor element, while providing a secure support for the same during the operation of the furnace.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire that only such' limitations shall be placed thereon as are imposed b the prior art or are specifically set forth xn the appended claims.,

L f I `claim as myl invention:

1.`An electric heatingelement for a furnace chamber defined by refractory walls comprising a. pluralityof spaced-apart relatively narrow, elongated refractory members extending beyond the inner surface of said walls into said chamber each having a plurality of spaced apart transversely extending slots of substantially-L-shape adjacent to the inner surface thereof, and a plurality of end-connected convolutions of relatively heavy and self-supporting-resistor material located in said slots and extending openly between said refractory members.

2. In an electric resistor-furnace the combination with a plurality of walls spaced ,apart to enclose a furnace chamber, of a operative position in said slots by being moved in a direction at right angles to the 1 plane of the resistor. y f

3. An electric resistor-supporting means comprising an elongated refractory member having a plurality of transversely extending slots of substantially L-shape with an enlarged inner-end portion therein.

4. An electric resistor-supporting means comprising an elongated refractory member having a plurality of spaced integral singleflange projections in one surface thereof.

5. An electric resistor-supporting means comprising an elongated refractory member having a plurality of spaced symmetrical integral projections on one surface thereof, each of said .projections having aV single overhung flange.

6. An electric furnace comprising a furnace chamber provided with side and top walls, a refractory innerl lining forV said walls consisting of spaced apart sections, refractory resistor-supporting members l0- cated in the spaces between said lining sections and projecting into said furnace chamber and having a plurality of slots of substantially L-shape insaid pro'ecting portion and a resistor element in sai slots.

7. An electric furnace comprising a plurality of refractory walls and a refractory roof and resistor-su porting members supported respectivel liy said walls and said roof, each of sai members havinga pluralityV of integral. single-flange projections on one surface thereof, and resistor members supported by Lsaid projections.

8. An electric furnace comprising a furnace chamber provided with side and top walls, a refractory inner lining for said walls consisting of spaced-apart sections, each section edge having an overhanging flange, a plurality of refractory members of substantially T-shape located in the spaces between said lining sections and su ported by said overhanging flanges, each refi'actory member having a plurality of integral rojections of substantially L-sha e exten 'ng into said furnace chamber, an a resistance element consistingof end-connected convolutions supported by said projections of l.- shape and being substantially self-sustaining between said projections.

9. An electric furnace comprising a furnace chamber provided with side and top walls, a refractory inner lining for said walls consistingr of spaced-apart sections, a plurality of refractory resistor-supporting members located between and supported by l0 said sections and projecting part having a plurality-of slots 'of substantially L-shape therethrough and a resistance element consisting of end-connected convolutions located in said slots and being substantially selfsupporting between said supporting members.

In testimony whereof, I have hereunto subscribed my name this 18th day of April THOMAS A. REID. 

